Bosch Drive Units may only be purchased as a direct replacement for a faulty or warrantied drive-unit on an existing bike. The purchase of a new drive-unit can only occur as a one for one exchange with the old unit. Old units need to be returned to Bosch eBike USA. To initiate a warranty replacement, please contact Bosch Technical support directly at 844.723.2453 or [email protected]. If you are looking to purchase a non-warranty drive unit for direct replacement, approval from the OE bicycle manufacturer is required. Please contact that manufacturer for additional information and approval.